An exhaust gas from a diesel engine contains nitrogen oxides and black smoke particles (particulate) that are harmful to human bodies. Among them, the black smoke particles consist mainly of carbons. To remove the particles, various fine particle-removing devices have already been proposed. For example, JPA 01-77715 discloses such a device that employs a ceramic filter of cross-flow type. In this device, an intake path and an exhaust path for an exhaust gas are arranged in such a relation that they cross with each other at right angle via a partition of gas-permeable porous solid (ceramic). The black smoke particles are captured at the partition when the introduced exhaust gas penetrates through the partition.
JPA 01-159408, for example, also discloses a fine particle-removing device that utilizes a ceramic filter with a honeycomb structure. In this device, a gas-permeable porous solid is also used as partitions that form respective cells in the honeycomb structure. In addition, one end with respect to a first group of cells and the other end with respect to a second group of cells are closed. Then, an exhaust gas is introduced into the second group of cells from the first group of cells via respective partitions so as to capture the black smoke particles at each partition.
Either of the above-mentioned conventional devices for removing fine particles in exhaust gases is, however, a system for filtering the black smoke particles by allowing them to penetrate through the partition of a porous material. Accordingly, there is a disadvantage that a resistance against the exhaust gas flow is increased and the output of the diesel engine is lowered. In addition, the black smoke particles captured at the partition are finally burned up to dispose. At this moment, another disadvantage is caused because ashes remained after burning up may stay over the surface of the partition and clog the filter gradually, lowering the filter function finally, increasing the exhaust resistance further more and lowering the output of the engine. For this reason, adapted in the art is a method of rinsing back the black smoke particles captured at the surface of the ceramic partition and burning them up after transferring them to another location. Therefore, the device disadvantageously becomes a larger scale.